Photographic amusement device and method of making the same



SAME* Nov. 12, 1935.

H. PELs PHOTOGRAPHIC AMUSEMENT DEVICE AND METHOD OF MAKING THE Filed Sept. 2'?, 1933 Doma KING My lmruu-s Aw: DAK. l STAR. nppzamd 1'n mwN- 213 u 4 'e/a//ne Ema/afan Per ava/bg ,4f/er e/ydasU/e ah/deye/a/pmenf l N VEN Ierer yPatented Nov. 12, 1935 UNITED s'rATlazsv PHOTOGRAPHIC AMUSEMENT DEVICE AND METHOD F `MAKING THE SAME Herbert Pels, New Rochelle, N. Y.

Application September 27, 1933, Serial No. 691,125 claims. (ci. eis-33)` My present'invention relates generally to the photographic art, and has particular reference, coordinately, to a new and unique amusement device and to an improved method of making 5 invisible but restorable photographic impressions.

While I have herein illustrated and shall hereinafter describe the manner in which certain phases of my invention are applicable to the production of a new and entertaining amusement in the nature of a guessing game or the like, it will be understood that, from many aspects, my invention has a far Wider applicability.

Briefly, my invention relates to animproved method of creating a photographic print with a bleached and totally invisible photographic imsodium thiosulphate subsequently to reduce the' mercurous chloride to metallic mercury.

I have found, however, that the action of mercuric chloride upon the silver of an ordinary photographic print, while producing a certain amount of eiacement `of the impression, is quite ineffective to produce a complete bleaching or obliteration of the impression, due probably to the fact that the silver chloride (or, in any event, the mixture of silver chloride and mercurous chloride) is not entirely white but has a. slight yellowish cast. Accordi-ngly, a faint but distinct impression always seems to remain visible, due to the contrast between the White paper back and the not-quite-White mixture of particles of silver chloride and mercurous chloride. This contrast is accentuated by the decided difference in textures between a layer or mass of these particles and the paper backing.

In accordance with my present inventio-n, I am enabled to bleach or render completely invisible a photographic impression, so that even the most painstaking scrutiny cannot discern the presence of any photographic impression whatsoy ever. In fact, a photographic print produced in accordance with my present invention has a surface that is absolutely blank and devoidof even the slightest trace of any impression; and the print may even be held between a source of light and the observer without revealing the fact that a predetermined photographic impression is carried thereby. This capability of the present in- E vention leads to the possibility of providing a unique amusement device which consists essentially of a bleached but restorable photographic print, the print bearing an invisible photographic impression of a recognizable subject, and bearing at the same time certain constantly visible indicia which afford clues to the identity of the subject. This photographic print is coupled with an extremely simple means for eiecting a restoration of the visibility of the impression, whereby the person employing the amusement device may preliminarily endeavor to guess the nature and identity of the subject subsequently capable of restoration to visibility by him. I contemplate that such amusement devices may be provided in series, furnished, for example, as premiums with commercial productsor the like, whereby children will not only seek to collect all the photographic prints of a given set or sets, but will be afforded the pleasure of indulging in an educational mys- Vtifying amusement in the restoration of each print of the set.

One of the salient characteristics of my present invention resulting in the successful production of a totally complete invisibility of a 3 photographic impression, lies in the treatment, with mercuric chloride, of a silver-halide-emulsion layer which has been photographically impressed, developed, but not fixed. Chemically, as is well-known, the development continues and completes the reduction of the silver-halide particles of the emulsion to metallic silver invarying degrees, depending upon the amount of light to which each particle has been subjected. Where such a layer is then immediately subjected to 40 the action of mercuric chloride, the deposited silver is transformed back. into silver chloride and forms a mixture with mercurous chloride. This mixture, I have found, is utterly indistinguishable, both in coloration and texture, from the 45 unreduced silver-halide portions of the emulsion. The resultant "invisibilize d print-may thus be said to bear a photographic impression formed of a mixture of silver chloride and mercurous chloride, the balance of the print comprising a y layer of gelatine emulsion with suspended, unreduced, silver-halide particles therein.-

l The subsequent restoration of the visibility` of the impression may then be expeditiously effected by me,ly treating the print with sodium thiov l i sulphate, which serves simultaneously to deposit metallicv mercury and to dissolve away all unreduced silver chloride and other silver-halide.`

The characteristics of my invention 'will be more fully appreciated upon reference to the accompanying drawing, in which- Figure 1 is a view of an invisibilized print formingan element of the present amusement.

device;

Figure 2 is a view of a preferred means for restoring the print; v

Figure 3 is a view similar to Figure il, showing the print in final restored and permanent condition;

Figure 4 is an enlarged cross-sectional view through the print, illustrating diagrammatically the effect of exposure to the desired photographic impression and the subsequent development;

Figure 5 is a view simiiar to Figure 4, showing diagrammatically the effect of the bleaching procedure; and ,V

igure 6 is a View similar to Figure 5, showing diagrammaticaliy the effect of the restoration step.

While any desired or suitable backing may be employed, l have illustratively shown a paper backing I0 of conventional character, the paper impression which may, for example, -be the portrait of a motion-picture actress, as indicated in Figure 3. The exposure of the paper is preferably, but not necessarily, accomplished by contact printing, this being performed in a safe light. The print is then subjected to the usual development, for example, in an ordinary developer such as metol-hydroquinone. The exposure and development result in the deposit of silver particles, for example, in the typical areal i2 of Figure 4. When this procedure has progressed to the desired degree, the developingaction is discontinued by preferably placing the print in a stop-bath composed, for example, of forty parts vof Water and one part of concentrated hydro- In accordance with my invention, however, I

scrupulously avoid any such procedure, and after rinsing the print briey, I immerse it at once into a bath composed, preferably, of approximately four ounces of water, one-quarter ounce of concentrated hydrochloric acid, and sixty-ve grains of mercuric chloride. The print is left in this bath until the image has completely disappeared, which ought to take about fteen or twenty minutes. The disappearance of the im' age is absolute, and leaves not the slightest visible trace, being caused by the vconversion oi' silver into a mixture of silver chloride and mercurous chloride. .A mass of Vthis mixture is formed wherever there was previously a mass of 4in Atexture and color from the balance of the emulsion which is composed of unreduced original silver salts. '5

After'the print has been washed thoroughly to remove the mercuric chloride, the production of the completely invisibilized photographic print is accomplished, subject, of course. to a drying action which is caused to take place in the dark. 10

The washing away oi.' the mercuric chloride may be hastened, if desired, by successive baths of hydrochloric acid, one toforty, followed by washing in water; butin such a case. it is advisable to treat the print with a ten per cent solution of formaldehyde for about twenty minutes, followed by a brief wash in water. Thev formaldehyde serves to compensate for the softening o! the gelatine by the acid.

The bleached print, when dried, is then ready 20 to be dispensed and used as one element of the amusement device. Preferably, the print is enclosed in a red glassine or waxed paper envelope or the like to guard it against undue exposure to strong light.

In accordance with my invention, the print is caused to bear certain constantly visible indicia such as those indicated at I3 in Figure 1. 'lhese indicia may appear either on the obverse face of the print il or on the reverse face. They may 30 be of any desired character, preferably affording a number of clues as to the identity and character of the subject of the bleached and invisible photographic impression.

To effect a restoration of the visibility of the Il impression, it is merely necessary to subject the print i4 to sodium thiosulphate.- the chemical effect being indicated in Figure 6. The sodium thiosulphat reacts with themercurous chloride to form metallic mercuryg-sodiumchloride, and 40 probably sodium tetrathionate, the mercury being the only insoluble resultant ingredient. The mercury deposits itself in the form of particles along the same areas that had previously been occupied by mercurous chloride. one of these areas 45 being designated diagrammatically by the reference numeral l5 of Figure 6. It B this deposit of mercury particles which enects a restoration of the image. The sodium thiosulphate simultaneously dissolves away all silver salts, includ- 50 ing the unreduced original silver-halides, whereby the layer VIl, in those places where there is no deposit of mercury.; consists of pure transparent gelatine. This permits the white o! the backing il to be visible, and produces the cong5 trast of black and white that is typical of the ordinary photographic print. The print is thus simultaneously restored and nxed, and is in a permanent and lasting condition after the process has been completed, subject, of course, to a 0o suitable washing oi.' the print and a drying thereof.

The application oi' the sodium thiosulphate, in carrying out the present amusement,is preferably accomplished by means of a sheet I6 of,

absorbent material, such as inexpensive yellow manila paper which has been impregnated with a solution of approximately two ounces thiosulphate of soda and ten ounces of water. The paper is left in this solution for about nve minutes and is then hung up to dry without rinsing. The invisibilized print of Figure 1, with the indicia I3 associated therewith, and the impregnated sheet I6 o! Figure 2'form the elements of my present amusement device. When used. to 7i of the finger tips insures contact and removes air bubbles. The image appears almost immediately, but contact is preferably continued for about live minutes to insure permanence. -The sheets are then separated, thesheet I6 being discarded, andV the print I4 is then washed in several changes of water for about iive minutes each and then permitted to dry. The result is indicated in Figure 3, and provides the user with a permanent card or print which may advantageously formone of a series that it is desirable to complete and own. v

Wherever I have used the termbleached herein, or in the appended claims, it will be understood to refer to an image obliteration of the character herein described, and not to a mere lightening or discoloring action, as the term bleaching usually connotes. Similarly, my reference to the immediate subjection of the print to they mercurio chloride, following its development, is to be construed as signifying the absence of any intermediate procedure such as the conventional fixing of the impression.

, In general, it will be understood that changes in the details, herein described and illustrated for the purpose of explaining the nature of my invention, may be made by those skilled in the art without departing from the spirit and scope of the invention as expressed in the appended claims. It is, therefore, intendedthat these details be interpreted as illustrative, and not in a limiting sense.

Having thus described my invention, and illustrated its use, what I claim as new and desire to secure by Letters Patent is- 1. The method of making a bleached but restorable photographic print, which consists in subjecting a layer' of silver-halide emulsion to the desired photographic impression, developing the layer to complete the reduction of the ailected silver-halide particles to thel desired degree, and then immediately subjecting said layer to mercurio chloride to transform the deposited silver into a. mixture of silver-halide and mercurous chloride, said mixture being indistinguishable from the unreduced silver-halide portions of Asaid layer, whereby the impression isrendered invisible but restorable by subsequent reduction of the mercurous chloride.

accosta 3 2. The method of bleaching and restoring a photographic print, which consists in subjecting a layer of silver-halide emulsion to'L the desired photographic impression, developing the layer to complete the reduction of the affected silver- V halide particles to the desired degree, then immediately subjecting said layer to mercurio chloride to transform the deposited silver into a mixture of silver-halide and mercurous chloride, said mixture being indistinguishable from the l .unreduced silver-halide portions 'of saidvlayer,

washing and drying the resultant bleached print, and subsequently subjecting the print to sodium thiosulphate to reduce the mercurous chloride to mercury and dissolvel away all silver-halide, whereby the print is simultaneously restored and fixed. l

3. In the herein-described method of making a bleached but restorable photographic print, the step which consists in treating a developed but unxed silver-halidefemulsion layer with mercuric chloride so as to transform the deposited silver into a mixture of silver-halide and mercurous chloride, said mixture being indistinguishable from the unreduced silverhalide portions of said layer.

4. The method of bleaching and restoring a photographic print, which consists in subjecting a layerof silver-halide emulsion to the desired photographic impression, developing the layer to complete the reduction of the affected silverhalide particles to the desired degree, then immediately subjecting said layer to `mercurio chloride to transformthe. deposited silver into a mixture of silver-halide and mercurous chlo- 35 ride, said mixture being indistinguishable from the unreduced silver-halide portions of said layer, washing and drying the resultant bleached print, impregnating and drying an absorbent sheet of material with sodium thiosulphate, and subsef .1,0

quently re-wetting and contacting the bleached print and the impregnated sheet, whereby the sodium thiosulphate reduces the mercurous chloride to mercury and simultaneously dissolves away all silver-halide, thereby restoring and iixing the print.

5. As a new article of manufacture, a bleached but restorable photographic print, comprising a backing, a layer of silver-halide emulsion thereon, said layer bearing portions conforming to a pre- 5o determined photographic impression, said portions comprising a mixture of silver chloride and mercurous chloride, the remainder of the layer comprising unreduced silver-halide.

HERBERT Pars. 

